a. Field of the Invention
This invention relates to a brake spider for a drum brake. In particular, the invention relates to a brake spider having improved formability, stiffness, strength and clearance as compared to conventional brake spiders.
b. Background Art
In a conventional drum brake, a brake drum rotates with a wheel or wheels proximate to one end of an axle. The drum defines a radially inner braking surface. A brake spider is disposed about the axle and a pair of brake shoes are pivotally mounted at one end to the brake spider. The opposite end of each brake shoe is engaged by an actuating member such as a cam or hydraulic piston or wedge to move the brake shoes between positions of engagement and disengagement with the braking surface of the brake drum.
Because of the significant loads imposed on the brake spider in certain heavy vehicles (e.g., vehicles with axles configured to bear weights of 26,000 pounds or more) and/or applications (e.g., school buses), brake spiders in such vehicles or applications have typically been manufactured by casting. Cast brake spiders, however, are relatively heavy and expensive to manufacture leading to undesirable weight and costs for vehicle manufacturers and operators. Lighter, stamped brake spiders have been used with lighter vehicles and/or less intense applications where the spiders are subject to lower loads, but have not been capable of use with heavier vehicles or more intense applications because they are unable to handle the more significant loads associated with such vehicles and applications.
The inventors herein have recognized a need for a brake spider that will minimize and/or eliminate one or more of the above-identified deficiencies.